[usb] Fix memory leak on close failure (#450)
[usb] Fix memory leak on close failure (#450)

Don't leak the libusb_device_handle memory when the handle closing
failed. Such failures should never happen under normal circumstances,
but it's still better to avoid such leaks.
GoogleChromeLabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector